Pine nut allergy
Allergy to pine nuts, often used in pesto.
About pine nut allergy
Pine nuts are the edible seeds of certain pine trees and, despite the name, are seeds rather than tree nuts in the botanical sense. True allergy to them is relatively uncommon but can be significant when it occurs. Like other seed and nut allergies it is usually IgE-mediated, with the immune system producing antibodies to pine-nut proteins that trigger a rapid release of histamine when the seed is eaten again.
Reactions typically start within minutes and can include an itchy mouth, hives, swelling, stomach upset, wheeze and, in serious cases, anaphylaxis. Pine nuts are a key ingredient in pesto and appear in salads, pastries and Mediterranean and Middle Eastern dishes, so they can be encountered unexpectedly. A separate, harmless phenomenon called "pine mouth" causes a bitter or metallic taste for a few days after eating some pine nuts; this is not an allergy and needs no treatment.
Diagnosis rests on the clinical history supported by skin-prick or specific-IgE blood testing, and occasionally a supervised food challenge. Management means avoiding pine nuts and checking pesto, sauces and bakery items carefully, as they are not always obvious on labels. Anyone at risk of a severe reaction should carry an adrenaline auto-injector; a severe reaction is a medical emergency requiring adrenaline and a 999 call.
Common triggers
- Pine nut and products containing it
Symptoms
- Itching or tingling in the mouth
- Hives, itching or eczema
- Swelling of the lips, face, tongue or throat
- Stomach cramps, nausea, vomiting or diarrhoea
- Wheezing or trouble breathing
- In severe cases, anaphylaxis
Avoidance & management
- Read ingredient labels every time
- Ask about ingredients and cross-contamination when eating out
- Keep the food out of shared cooking areas
- Carry prescribed antihistamines or an adrenaline auto-injector
- Seek emergency help for any severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.